Not at all--an FM receiver will do absolutely nothing to interfere with their radio system.
you cant receive with an fm receiver....you need an IEM receiver to get the signal which could have impact on the signal...
I'm not so sure about that. FM receivers can pick up IEM transmissions carried on FM band frequencies. The IEM system transmitters are set up to transmit a particular signal, and any FM receiver that has the ability to tune in that particular frequency can be used to illegally intercept the IEM transmission that is just floating around in the air. But no, you can't carry in your old Sony boombox and try to dial in the monitors on your FM radio, you'll need something that can tune about about, oh, 500 Mhz higher.
Sound quality depends on a great number of things, and are limited to the same kinds of things that limit other recordings. For scanner intercepts, one thing to keep in mind is that most scanners only have mono earphone jacks, intended for listening to mostly voice transmission, not music based professional audio. Further, the mix that is transmitted will more than likely be strange to listen to, not musically pleasing. Signal reception can depend on everything from distance from the transmitter to the particular weather pattern of the day. And then, you could show up to a show to try and record something, and you'll get nothing at all, depending on how the band sets up their gear. And then there is the blacklisting that will occur if you ever get caught working with wireless gear. Most legitimate tapers can't stand the idea of wireless taps. For example, it makes entrance inspections harder for them at the doors of some taper friendly bands. Following the big DMB IEM shakedown of 2001, many MusicToday bands have included a line in their taping policy strictly prohibiting wireless reveivers, so don't think the bands aren't aware of what is or has been going on. Realize that other tapers are aware of what's going on, too.
In the end, you have to ask if this kind of thing is worth the hassle. 9 times out of 10, the answer is "not really".
The argument here should be about the ethics of recording in this manner. The majority of the board has already decided that this kind of wire tapping is not a respectable way to obtain a recording. The biggest problem is the privacy issue. Some of the things that can be overheard on a wireless transmission are none of the public's business. That said, I'm still torn on the ethics of tapping non taping friendly bands. I personally feel that illegally recording a non taping band from a wireless source is equal to illegally recording them with a set of microphones, as long as private audible asides are not recorded, or edited out later. If someone wants to find out how to intercept these kinds of transmissions, the websites of Radio Shack and most major music retailers should fill you in on all you need to know. The internet is a big place, just poke around a bit. But nobody here will really support this behavior, and this will probably be the longest post anyone will write on the subject.
BTW - Craig Bromley is an idiot. He can't convert a FLAC down to a WAV, or set proper recording levels. I wouldn't try to seek him out for advice. At any rate, I think he's been pretty much harassed off the internet.